EDITOR,—Michael Sharpe and colleagues conclude that cognitive behaviour therapy leads to a sustained reduction in functional impairment for patients with the chronic fatigue syndrome.1 The levels of disability of the 60 patients who took part in the study suggest, however, that these patients do not represent a comprehensive cross section of patients with the syndrome. The 60 patients scored 60-78 on the Karnofsky scale assessing disability and so represent a different population from the 143 patients reported on …